Disassembling a Brushless Motor

P.S : Before disassembling the motor, if your item carries a warranty, opening and attempting your own repair, will void whatever warranty you have.

The following article contains a short tips on disassembling the brushless motor. Brushless motor should run smoothly from the lowest to maximum throttle with minimum vibration. We could easily listen to the smooth running noise of the motor without mounting the prop. Crashes from major to minor ones might cause unexpected damage to the motor; causing a rough run and noise, bad vibration and/or even twitching/stuttering at the start of the motor or during lowest throttle. Often, you might be able to hear a clicking or scrubbing noise when you rotate the motor manually. This is caused by the surface contact between the stator and the permanent magnets on the rotor; scratch lines can be seen on the stator and the rotor. Damaged bearings and bent shaft are the primary cause of this phenomenon. However, if the bearings and/or the shaft are replaced immediately, the motor might be restored to normal. Sometimes the motor has already been damaged badly and the phenomenon still present even after replacing the bearings and shaft.

To start disassembling the motor, various tools are required. The safest method is to use the bench press tool, however in this article, the disassembly procedure is done using the tools as shown in the picture below.

The first step involves in removing the circlip (E-ring), followed by the collar ring from the rear shaft using the pliers. Be cautious when removing the circlip because it might spring out. If you do not have any spares, do not lose it or bend it out of shape.

The second step is to pull and remove the rotor (the bell) from the stator (the body).

Notice that there are two bearings attached to the rear end and front end of the stator. The next step is to remove the bearings from the stator. Sometimes, the bearings are easy to remove, and some have a tight fit. Remove one of the bearings using barbeque skewer or any wooden stick to plug out the bearing from the stator. Usually, the front end bearing is easier to remove.

After you have managed to remove one of the bearings, use a pin punch tool to push the other bearing out from the stator.

Place the stator on the plastic wire spool / solder bobbin and carefully tap the pin punch tool using the hammer until the bearing drops out from the stator.

Now you can replace the old bearings with the new ones. You might use the pin punch tool to push the new bearings into place. Just lightly tap to prevent any damage to the new bearings.

The next procedure is to remove the shaft from the rotor (the bell). Use the allen key to remove the set screw on the rotor.

The final step is to push the shaft out from the rotor using the similar pin punch tool technique implemented previously to remove the bearings.

Now you can replace the shaft with the new one. Carefully tap the new shaft back to the rotor. Make sure the flat surface on the shaft is position directly above the hole for the set screw.

Assemble back the rotor to the stator and followed by inserting back the collar and the circlip to the shaft’s rear end. You are done!

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